struct chanl_status{
    int target_id;
    int pkt_id;
    int is_acked;
    double send_time;
    double recv_time;
    double ack_time;
    int retry_times;

    chanl_status(int targetid=0,int pktid=0,
        int isacked=0):target_id(targetid),
        pkt_id(pktid),is_acked(isacked),send_time(0),
        recv_time(0),ack_time(0),retry_times(0){}
    chanl_status(const chanl_status& another){}
};